1. Field of the Invention
The invention disclosed in this specification and the like relates to a display device and an electronic device including the display device.
2. Description of the Related Art
With the recent rapid spread of portable information terminals such as smartphones, improvement in their performance has progressed rapidly. Their screens have been increased in size and resolution, and emphasis has been on power consumption of display devices with increasing screen resolution. A typical example of display devices is a liquid crystal display device including a liquid crystal element. In each of pixels arranged in a matrix in a liquid crystal display device, a transistor serving as a switching element, a liquid crystal element electrically connected to the transistor, a capacitor connected to the liquid crystal element in parallel, and the like are provided.
As a semiconductor material of a semiconductor film of the transistor, a silicon semiconductor such as amorphous silicon or polysilicon (polycrystalline silicon) is generally used.
Metal oxides having semiconductor characteristics (hereinafter referred to as oxide semiconductors) can be used for semiconductor films in transistors. For example, techniques for manufacturing transistors using zinc oxide or an In—Ga—Zn-based oxide semiconductor are disclosed (see Patent Documents 1 and 2).